The Influence of Lung Cancer Screening Tests on Smoking Cessation
Smoking remains the number one cause of preventable death in the United States, yet approximately 25% of Americans over age 12 (60 million people) reported current smoking in 2003. Fortunately, the risk of dying from a smoking-related cause decreases fairly sharply after a smoker quits—on average by 50% for those who stop by age 65. Unfortunately, smoking cessation rates are low—5% to 7% annually for the general smoking population, and relapse rates are high. Thus, finding and using effective smoking cessation programs is a national health priority.
Research shows that people tend to underestimate their risk of disease, so it is often a major challenge to convince them that their unhealthy behaviors really do pose a health threat. In the case of smoking, researchers have been investigating the use of cancer screening to bolster smoking cessation rates.
While some studies have found higher cessation rates among smokers who received an abnormal (positive) computed tomography scan (CT scan) result, others have not. A new study out of the Mayo Clinic, published in the May 15, 2005 issue of Cancer (available online April 11, 2005), shows that smokers who received several positive CT scan results were more likely to quit.
About the Study
In 1999, researchers enrolled 1,520 current and former smokers to undergo a series of CT scans for lung carcinoma. While CT scans are primarily used to detect lung cancer as early as possible in order to increase the chance of successful treatment, this study focused on how CT screening affects smoking behavior.
The participants were between 50 and 85 and predominantly white, with equal numbers of men and women. They had no symptoms of lung cancer, no history of cancer within five years, and no other current serious illness.
The study population was composed of two groups of participants:
- 926 smokers, who smoked an average of 25 cigarettes a day for an average of 39 years prior to enrollment
- 594 former smokers, who had an average history of a pack-a-day habit for 20 years and had quit within the past 10 years
Participants underwent CT scans at the start of the study and then annually for three years. At each session, the researchers gathered information on smoking status, including quit dates or number of cigarettes smoked per day. If a potentially cancerous nodule was detected, the participant was recommended for a follow-up CT scan within six months.
At the initial scan, 57% of the current smokers were found to have an abnormal CT scans, 22% had abnormal findings at the first annual visit, and 15% had abnormal findings at the second annual visit.
Fourteen percent (14%) of current smokers reported having quit smoking by the first annual visit, 22% by the second annual visit, and 24% by the third annual visit. Each year, about 12% of participants reported quitting in the past year (a rate much better than the national average), but the annual relapse rate remained high: 28% to 51%.
Current smokers were more likely to quit if their CT scan result was abnormal the previous year. And, as the number of abnormal CT scans increased, so did their quit rates: participants with 0, 1, 2, and 3 previous abnormal CT scan results were 20%, 24%, 28%, and 42% more likely to quit smoking by the final scanning session, respectively.
On the other hand, CT scan results had no bearing on whether or not former smokers remained abstinent or began smoking again.
While these findings are illuminating, the study was limited by the fact that the researchers did not enroll a “control” group of smokers and former smokers who did not undergo CT scanning. Future studies, therefore, are needed to confirm that CT scanning improves cessation rates more than not scanning. Also, this study population—all residents of Minnesota and mostly Caucasian—may not represent the general smoking population. Finally, all the participants volunteered to undergo CT scanning, which might indicate they were already more aware of their risk of disease. This higher perceived risk may have contributed to the high cessation rates in this study.
How Does This Affect You?
These findings suggest that cessation interventions that employ multiple cancer screenings—as opposed to a one-time screening—may be more useful in helping high-risk smokers quit. Smokers who received the most abnormal CT scan results in this study were also the most likely to quit (42% likelihood over three years). Despite some evidence to the contrary in the past, CT screening may be an effective way to facilitate smoking cessation as long as the results are worrisome.
But, what about smokers who continue to receive good news about their scans? In this study, normal CT scans still led to cessation rates that were higher than the national average—20% compared to 5-7%.
Nicotine addiction is a complex behavior requiring equally complex cessation interventions. While it is unlikely that CT scanning programs alone will dramatically increase cessation rates nationwide, this study suggests that they may motivate some smokers, particularly those at the highest risk, to finally quit.
Prevention and Cessation of Cigarette Smoking: Control of Tobacco Use (PDQ®)
National Cancer Institute
Tobacco and Cancer
American Cancer Society
Substance Abuse and Mental Health Services Administration (SAMHSA). 2003 National Survey on Drug Use & Health: Results. Available at: http://www.oas.samhsa.gov/NHSDA/2k3NSDUH/2k3results.htm#fig4.7 . Accessed on April 13, 2005.
Townsend CO, Clark MM, Jett JR, Patten CA, Schroeder DR, Nirelli LM, et al. Relation between smoking cessation and receiving results from three annual spiral chest computed tomography for lung carcinoma screening. Cancer. 2004; 103(10). Published online April 11, 2005 in Wiley InterScience (www.interscience.wiley.com).
Last reviewed April 15, 2005 by ]]>Richard Glickman-Simon, MD]]>
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